Scientists have long known that spitting cobras don't actually spit. Rather, muscle contractions squeeze the cobra's venom gland, forcing venom to stream out of the snake's fangs, explains Bruce Young, a researcher at the University of Massachusetts. The muscles can produce enough pressure to spray venom up to 6 feet (nearly 2 meters).

To be effective, venom — a cocktail of neurotoxins and tissue-attacking poisons — must make contact with an attacker's eyes, where it causes severe pain and possibly blindness.

Turns out the venom does not hit a victim in just one spot. Instead, the venom lands in complex geometric patterns.

Young and his team now have figured out how this spray is generated. They used high-speed photography and electromyography (EMG) to detect contractions of cobra head and neck muscles. The snakes engage their head and neck muscles a split second before "spitting" to rotate their heads, then jerk them from side to side.

"The venom-delivery system functions to propel the venom forward while the [head and neck] muscles produce rapid oscillations of the head that … disperse the venom, presumably maximizing the chance that a portion of the spat venom will contact the eye," the researchers write in the journal Physiological and Biochemical Zoology.